The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station.

‘One can envision villages in India and Africa not long from now purchasing an affordable basic power system based on this technology.’

The device bears no resemblance to Mother Nature’s counterparts on oaks, maples and other green plants, which scientists have used as the model for their efforts to develop this new genre of solar cells.

About the shape of a poker card but thinner, the device is fashioned from silicon, electronics and catalysts, substances that accelerate chemical reactions that otherwise would not occur, or would run slowly.

Placed in a single gallon of water in a bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day, Nocera said.

It does so by splitting water into its two components, hydrogen and oxygen.

The hydrogen and oxygen gases would be stored in a fuel cell, which uses those two materials to produce electricity, located either on top of the house or beside it.

Nocera, who is with the Massachusetts Institute of Technology, points out that the ‘artificial leaf’ is not a new concept.

The first artificial leaf was developed more than a decade ago by John Turner of the U.S. National Renewable Energy Laboratory in Boulder, Colorado.

Although highly efficient at carrying out photosynthesis, Turner’s device was impractical for wider use, as it was composed of rare, expensive metals and was highly unstable — with a lifespan of barely one day.

In order to detect signs of past or present life on Mars — if it is in fact true that we’re related — then a promising strategy would be to search for DNA or RNA, and specifically for particular sequences of these molecules that are nearly universal in all forms of terrestrial life. That’s the strategy being pursued by MIT research scientist Christopher Carr and postdoctoral associate Clarissa Lui, working with Maria Zuber, head of MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS), and Gary Ruvkun, a molecular biologist at the Massachusetts General Hospital and Harvard University, who came up with the instrument concept and put together the initial team. Lui presented a summary of their proposed instrument, called the Search for Extra-Terrestrial Genomes (SETG), at the IEEE Aerospace Conference this month in Big Sky, Mont.

The idea is based on several facts that have now been well established. First, in the early days of the solar system, the climates on Mars and the Earth were much more similar than they are now, so life that took hold on one planet could presumably have survived on the other. Second, an estimated one billion tons of rock have traveled from Mars to Earth, blasted loose by asteroid impacts and then traveling through interplanetary space before striking Earth’s surface. Third, microbes have been shown to be capable of surviving the initial shock of such an impact, and there is some evidence they could also survive the thousands of years of transit through space before arriving at another planet.